/// <summary>
/// Calculates the average amplitude in the frequency just above the whistle.
/// If it contains above threshold acoustic content, this is unlikely to be a whistle.
/// </summary>
/// <param name="ev">The event.</param>
/// <param name="sonogramData">The spectrogram data as matrix with origin top/left.</param>
/// <param name="bufferBins">THe badnwidth of the buffer zone in bins.</param>
/// <param name="converter">A converter to convert seconds/Hertz to frames/bins.</param>
/// <returns>Average of the spectrogram amplitude in buffer band above whistler.</returns>
public static double GetAverageAmplitudeInNeighbourhood(SpectralEvent ev, double[,] sonogramData, int bufferBins, UnitConverters converter)
{
var bottomBufferBin = converter.GetFreqBinFromHertz(ev.HighFrequencyHertz) + 5;
var topBufferBin = bottomBufferBin + bufferBins;
var frameStart = converter.FrameFromStartTime(ev.EventStartSeconds);
var frameEnd = converter.FrameFromStartTime(ev.EventEndSeconds);
var subMatrix = MatrixTools.Submatrix <double>(sonogramData, frameStart, bottomBufferBin, frameEnd, topBufferBin);
var averageRowDecibels = MatrixTools.GetRowAverages(subMatrix);
var av = averageRowDecibels.Average();
return(av);
}
public void TestBackwardsAndForwardsConversionSpectrograms(int frame, int bin)
{
UnitConverters converter = new UnitConverters(
60,
22050,
512,
256);
var endFrame = frame + 1;
var secondsStart = converter.GetStartTimeInSecondsOfFrame(frame);
var secondsEnd = converter.GetEndTimeInSecondsOfFrame(endFrame);
var hertz = converter.GetHertzFromFreqBin(bin);
var outFrame = converter.FrameFromStartTime(secondsStart);
var endOutFrame = converter.FrameFromEndTime(secondsEnd);
var outBin = converter.GetFreqBinFromHertz(hertz);
Assert.AreEqual(frame, outFrame, $"Frames do not match, expected: {frame}, actual: {outFrame}, seconds was: {secondsStart}");
Assert.AreEqual(endFrame, endOutFrame, $"Frame ends do not match, expected: {endFrame}, actual: {endOutFrame}, seconds was: {secondsEnd}");
Assert.AreEqual(bin, outBin, $"Bins do not match, expected: {bin}, actual: {outBin}, hertz was: {hertz}");
}